Full Stack Engineer

About the role

NUMBERO, a fast‑growing German tech startup, is looking for a Full Stack Engineer to join its Valencia development hub. You will work on a production‑grade Node.js backend and a React + TypeScript frontend while integrating data and AI services that power after‑sales solutions for car dealerships.

Key responsibilities

• Develop and maintain full‑stack features using React, TypeScript, Express.js and Node.js.
• Design database schemas, write migrations and optimise MySQL/MariaDB queries.
• Build and expose REST APIs and integrate them with the frontend.
• Implement background job processing, scheduled tasks and asynchronous workflows (e.g., BullMQ).
• Contribute to AI‑driven features, LLM integrations and prompt engineering.
• Connect web applications to data platforms such as PowerBI, Databricks and Azure Data Lake Storage.
• Ensure code quality, high test coverage and participate in code reviews.
• Monitor, debug and maintain production systems independently.

Required profile

• Strong ownership mindset, delivering end‑to‑end features without close supervision.
• Ability to collaborate with technical and business stakeholders.
• Experience working in a fast‑paced, autonomous environment.

Required skills

• React
• TypeScript
• HTML5 & CSS3 (Bootstrap, Tailwind CSS)
• REST API design & consumption
• Git
• Node.js & Express.js
• MySQL / MariaDB
• Redis (caching, job queues, distributed locking)
• BullMQ or similar queue system
• Docker & Docker Compose
• JWT authentication & role‑based access control
• Cron job scheduling
• Databricks
• Azure Data Lake Storage
• PowerBI
• LLM integrations & prompt engineering